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Analysis of the atrial repolarization wave in dogs with third-degree atrioventricular block

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  • 1 Cardiology Division, Clinica Veterinaria Malpensa, Viale Marconi 27, Samarate (VA) Italy.
  • | 2 Medivet Veterinary Clinic Richmond, 171 Lower Richmond Rd, Mortlake, SW14 7HX London, England.
  • | 3 Cardiology Division, Clinica Veterinaria Malpensa, Viale Marconi 27, Samarate (VA) Italy.

Abstract

Objective—To characterize the electrocardiographic features of the atrial repolarization (Ta) wave in dogs with third-degree atrioventricular (AV) block.

Sample—ECGs of 36 dogs with third-degree AV block and no identifiable structural heart diseases.

Procedures—Standard 12-lead ECGs were acquired with a digital system, and measurements were manually edited.

Results—A Ta wave was detectable in all dogs for at least 1 ECG lead. The Ta wave had negative polarity in leads I, II, III, and aVF and positive polarity in leads aVL and aVR, with a mean electrical axis of −114.26°. Mean duration and mean amplitude of the Ta wave in lead II were 140.2 milliseconds and −0.09 mV, respectively, with the ratio for the Ta-to-P wave duration of 2.3 and the ratio of Ta-to-P wave amplitude of −0.35. Significant correlations were found between the Ta wave duration and duration of the P-Ta interval, Ta wave amplitude and the ECG lead, Ta wave duration and body weight, and duration of the P-Ta interval and atrial rate. Measurements of the Ta wave were repeatable.

Conclusions and Clinical Relevance—Measurements of the Ta wave in dogs with third-degree AV block were repeatable. The values for the Ta wave reported here can be used as reference values for dogs with AV conduction disturbances and an echocardiographically normal atrial size. Further studies are needed to validate these results in dogs with structural heart diseases.

Contributor Notes

Presented in abstract form at the American College of Veterinary Internal Medicine Forum, New Orleans, June 2012.

The authors thank Dr. Nicoletta Vitale for assistance with the statistical analysis.

Address correspondence to Dr. Santilli (rasantil@alice.it).